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Abstract

Differences in light scattering properties of a tumorigenic and a non-tumorigenic model for tissue were demonstrated using a variety of light scattering techniques, the majority of which are in vivo compatible. In addition to determining that light scattering differences exist, models for the microarchitectural changes responsible for the light scattering differences were developed.

Figures (13)

Schematic of the fiber optic system. a) Components of the fiber-optic system. b) Schematic of the distal end of the probe. There is a polarizer on the top left, covering delivery fiber P and collection fibers 1 and 4 that polarizes the light horizontally. A polarizer on the bottom left, covering only fiber 3, polarizes the light vertically. There is no polarizer over delivery fiber U and collection fiber 2.

An image of the log of the light scattering intensity of plateau phase Rat1 cells used for calculating the reduced scattering coefficient. The peripheral circle used for calculating the reduced scattering coefficient is shown in black. Contours of log intensity are in white. The point of laser incidence is defined as (0,0).

Images of log intensity from the tumorigenic model (Rat1-T1 cells harvested in the exponential phase of growth). a) crossed polarizers, log(I⊥). b) parallel polarizers, log(I∥). The polarizaton of the excitation light is vertical in these images.

Images of log(I∥/I⊥). a) Non-tumorigenic model (Rat1 cells harvested in the plateau phase of growth). b) Tumorigenic model (Rat1-T1 cells harvested in the exponential phase of growth.) The scale is the same in panels a and b. c) The image in a) subtracted from the image in b).

Values along horizontal and vertical lines through images of log(I∥/I⊥) for the tumorigenic model (exponential Rat1-T1 cells) (red) and non-tumorigenic model (plateau Rat1 cells) (blue). Averages along with the standard deviations of multiple measurements are shown.

a) The value of I1/I3 determined from fiber optic probe measurements of Rat1-T1 cells harvested in the exponential phase of growth (red) and Rat1 cells harvested in the plateau phase of growth (blue). b) Same as a) but for I1/I4.

Angularly resolved light scattering measurements. a) polarizers perpendicular to the scattering plane. b) polarizers parallel to the scattering plane. The data have been normalized to have the same intensity from 30° – 50°.

Differences in simulation and experimental results for the tumorigenic model minus the non-tumorigenic model. The error bars are standard deviations of either multiple experiments or multiple simulations. a) Difference in log(I∥/I⊥). b) Differences in the slope of the unpolarized data determined by a straight line fit to the data from 500 – 800 nm. c) and d) Differences in I1/I3 and I1/I4.

Simulation of angularly resolved light scattering measurements. a) polarizers perpendicular to the scattering plane. b) polarizers parallel to the scattering plane. See the caption of Fig. 12 for the definition of Simulation 2.

Tables (2)

Table 2. Light scattering differences. Rat1-T1e means exponential phase Rat1-T1 cells and Rat1p means plateau phase Rat1 cells. All results are at a t-test significance level of 0.05 or better. For the log(I∥/I⊥ a t-test a significant results means that a point along the horizontal or vertical line had a significantly different value.

Model of the size and refractive indices of scattering structures.

Table 2.

Light scattering differences. Rat1-T1e means exponential phase Rat1-T1 cells and Rat1p means plateau phase Rat1 cells. All results are at a t-test significance level of 0.05 or better. For the log(I∥/I⊥ a t-test a significant results means that a point along the horizontal or vertical line had a significantly different value.

Cell comparison

Slope steepness

I1/I4

I1/I3

log(I∥/I⊥)

Rat1-T1E vs Rat1P

Rat1-T1E>Rat1P

Rat1-T1E<Rat1P

Rat1-T1E>Rat1P

-

E vs P (Rat1-T1)

E>P

E<P

E>P

E>P

E vs P (Rat1)

E>P

E<P

E>P

-

Rat1-T1 vs Rat1 (E)

-

-

-

-

Rat1-T1 vs Rat1 (P)

-

Rat1-T1>Rat1

-

-

Tables (2)

Table 1.

Model of the size and refractive indices of scattering structures.

Distribution

Average size (μm)

number density (cm-3)

Ellipticity

nmedium

nscatterer

1

0.01126±0.88470

1.0692*1013

0.25

1.33

1.46

2

0.61150±0.62900

2.0066*1010

0.5

1.35

1.40

3

4.86180±0.13800

7.898*108

0.851

1.37

1.39

Table 2.

Light scattering differences. Rat1-T1e means exponential phase Rat1-T1 cells and Rat1p means plateau phase Rat1 cells. All results are at a t-test significance level of 0.05 or better. For the log(I∥/I⊥ a t-test a significant results means that a point along the horizontal or vertical line had a significantly different value.